A 45-year-old woman with rheumatoid arthritis has Hb 9.6 g/dL, MCV 78 fL. Iron studies show serum iron 30 mcg/dL (low), TIBC 220 mcg/dL (low), transferrin saturation 14%, and ferritin 180 ng/mL. Which mechanism best explains these values?

• A Defective globin chain synthesis reducing heme demand
• B Absolute depletion of body iron stores from chronic blood loss
• C Hepcidin-mediated blockade of ferroportin trapping iron in macrophages ✓
• D Autoimmune destruction of duodenal enterocytes impairing absorption

Explanation

Inflammation raises interleukin-6, driving hepatic hepcidin release. Hepcidin binds ferroportin on enterocytes and macrophages, internalizing it, which blocks gut iron absorption and iron release from stores. This produces low serum iron, low TIBC, and normal or high ferritin. The high ferritin kills the distractor of absolute deficiency, where ferritin falls below 15 to 20 ng/mL and TIBC is elevated rather than reduced.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.